Pen



FIG. 1 is a perspective view of a pen showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational view thereof; the left side elevational view is a mirror image of the right side;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The broken lines showing the push button, clip, clip attachment portion, details on the grip, and writing tip housing are included for the purpose of illustrating environment and form no part of the claimed design. 

The ornamental design for a pen, as shown and described. 